1. Field of the Invention
The present invention relates to an endoscope system, and in particular to an endoscope system which scans an object to acquire an image.
2. Description of the Related Art
For endoscopes in a medical field, various techniques for reducing a diameter of an insertion portion inserted into a body cavity of a subject have been proposed in order to reduce a burden on the subject. As an example of such techniques, a scanning-type endoscope which does not have a solid image pickup device in a portion corresponding to the insertion portion described above, and a system configured being provided with the scanning-type endoscope are known.
More specifically, the system provided with the scanning-type endoscope is configured, for example, to two-dimensionally scan an object in a preset scan pattern by swinging a distal end portion of a light guiding fiber which guides light emitted from a light source portion, receive return light from the object by a light-receiving fiber and generate an image of the object based on the return light received by the light-receiving fiber.
On the other hand, among optical fibers, there are, for example, some provided with such an optical characteristic that transmittance is reduced at time of being exposed to a radiation such as an X ray and that recovery of the reduction of the transmittance is accelerated by adding light having a relatively high intensity.
For example, Japanese Patent Application Laid-Open Publication No. S58-73332 discloses a technique for accelerating recovery of transmittance of an optical fiber which has been reduced by exposure to a radiation.
More specifically, Japanese Patent Application Laid-Open Publication No. S58-73332 discloses such a configuration that, in an endoscope, a transmittance of an optical glass fiber bundle for image transmission is recovered close to an initial transmittance (at time of manufacture) by providing a predetermined optical device (prism or mirror) for deflecting light emitted from a light emission end face of an optical fiber bundle for light transmission in an insertion portion and arranging the predetermined optical device at a position where the emitted light is caused to be incident on an image incident surface of the optical glass fiber bundle for image transmission.